This invention relates to a novel process for the production of prostaglandin F.sub.2.sub..alpha. and its analogs.
According to the procedure of E. J. Corey et al., J. Am Chem. Soc., Vol. 93 (1971), p. 1491, the lactone of the formula ##SPC3##
Is converted into prostaglandin F.sub.2.sub..alpha. in several steps, according to the following reaction scheme: ##SPC4##
In the above reaction scheme, BP = p-biphenyl and THP = tetrahydropyranyl-2.
After saponification (a) of the lactone of Formula I, the bis(tetrahydropyranyl) ether (III) is produced with dihydropyran in the presence of p-toluenesulfonic acid (b). The reduction of the lactone (III) with diisobutylaluminum hydride (c) results in the production of lactol of Formula IV. By means of the Wittig reagent from 4-carboxybutyltriphenylphosphonium bromide and methylsodiummethanesulfinyl (d), the intermediate product of Formula V is obtained, resulting in PGF.sub.2.sub..alpha. (VI) by hydrolysis (e) of the tetrahydropyranyl groups.
The above-described synthesis comprises five stages, proceeding by way of intermediate products which are sensitive to acids and thus difficult to handle.
It is an object of this invention to provide a simplified process for the preparation of the physiologically valuable prostaglandin F.sub.2.sub..alpha. and the analogs thereof.
It has now been found, according to the process of this invention, which is suitable for the production of prostaglandin F.sub.2.sub..alpha. and the analogs thereof, that three steps of the five stage conventional synthesis can be eliminated.